Transcript HULL FRAMING SYSTEMS - IHMC Public Cmaps (2)

HULL FRAMING
SYSTEMS
GROUP C
DMS(DO)
QUESTION
Describe and compare transverse and
longitudinal framing systems and explain the
need for combination framing system.
FRAMING SYSTEMS
There are three possible ways to fit the secondary supporting
members:



Transverse Framing System
Longitudinal Framing System
Combined or Mixed Framing System
TRANSVERSE FRAMING
SYSTEM



The hold frames are fitted
transversely
Longitudinal deck girders support
the transverse deck beams
Longitudinal strength in a
transversely framed ship is
provided by:



The centre girder, the shell plating
and inner bottom plating
By the deck plating outboard of
hatch and machinery casing
openings
By a number of large, widely
spaced longitudinal members e.g.
longitudinal deck girders
TRANSVERSE FRAMED OIL
TANKER
LONGITUDINAL FRAMING
SYSTEM

All secondary supporting members are
fitted the longitudinal direction and are
known as longitudinals
 The system consists of many small,
closely spaced longitudinals supporting
the plating directly and being supported
in turn by a few largely spaced
longitudinals
 It is in tankers that this system in its
purest form is employed
 They also contribute to the longitudinal
strength of the ship, making the
longitudinal framing system more
structurally efficient than the transverse
system
LONGITUDINALLY FRAMED OIL
TANKER
COMPARISON

No contribution to the ship’s
resistance to longitudinal bending.

More resistant to buckling
between longitudinal stiffeners
when subjected to compressive
stresses while bending in seaway.

Not optimal from the standpoint of
structural efficiency, i.e. achieving
the required strength for the least
weight.

Superior structural efficiency
because most of the plating
stiffeners are in the fore and aft
direction.

The intrusion of deep webs into prime cargo spaces for ships carrying
packaged cargo is a disadvantage of longitudinal framing system.

As the hull narrows toward bow and stem, the girth necessary reduces.

Difficulties in construction arise when the longitudinal frames converge so
closely.

For this reason, transverse framing is usually resorted to at the bow and stem
of longitudinally framed ships.
COMBINED FRAMING SYSTEM

A combination of both transverse and
longitudinal framing is adopted in the
same cross section of the ship.

Longitudinal framing is used in the
bottom and decks.

This has the advantage of extra
longitudinal strength and resistance
to compressive plate buckling.

Transverse framing is used in the
sides.

This precludes the need for deep
webs that might inhibit efficient cargo
stowage.
COMPOSITELY FRAMED OIL
TANKER
REFERENCES
 Ship
Powering and Construction Notes
 Naval Architecture Lectures on the web

http://web.nps.navy.mil/~me/tsse/NavArchWe
b/lectures.htm/